 /*******************************************************************************
  * Copyright (c) 2005 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
  * IBM Corporation - initial API and implementation
  *******************************************************************************/
 package org.eclipse.core.commands.operations;

 import org.eclipse.core.runtime.IAdaptable;
 import org.eclipse.core.runtime.IStatus;
 import org.eclipse.core.runtime.Status;

 /**
  * <p>
  * An operation approver that enforces a strict linear undo. It does not allow
  * the undo or redo of any operation that is not the latest available operation
  * in all of its undo contexts. This class may be instantiated by clients.
  * </p>
  *
  * @since 3.1
  */
 public final class LinearUndoEnforcer extends LinearUndoViolationDetector {
     /**
      * Create an instance of LinearUndoEnforcer.
      */
     public LinearUndoEnforcer() {
         super();
     }

     /*
      * Return whether a linear redo violation is allowable. A linear redo violation
      * is defined as a request to redo a particular operation even if it is not the most
      * recently added operation to the redo history.
      */
     protected IStatus allowLinearRedoViolation(IUndoableOperation operation,
             IUndoContext context, IOperationHistory history, IAdaptable uiInfo) {
         return Status.CANCEL_STATUS;
     }

     /*
      * Return whether a linear undo violation is allowable. A linear undo violation
      * is defined as a request to undo a particular operation even if it is not the most
      * recently added operation to the undo history.
      */
     protected IStatus allowLinearUndoViolation(IUndoableOperation operation,
             IUndoContext context, IOperationHistory history, IAdaptable uiInfo) {
         return Status.CANCEL_STATUS;
     }

 }

